Drill bits used in earth boring operations undergo high stresses and forces. Drill bits, such as Polycrystalline Diamond Compact or Polycrystalline Diamond Cutter “PDC” bits, may be employed to drill through hard earth formations such as rock and coal, which may be abrasive and cause certain portions of the bit to erode. When material forming a pocket supporting the cutters erodes, cutters may become loose and may even separate from the bit and be lost in the wellbore. The loss of cutters reduces the drilling effectiveness of the bit, and their replacement may be costly and time consuming. To avoid loss of cutters, eroded bits may be repaired such that the cutter pockets are rebuilt to be able to support a replacement cutter.
Cutter pockets may be repaired using a puddle torch to apply a nickel based hardfacing material, such as TP MB40 powder available from Technogenia. These repaired PDC bits may continue to be susceptible to severe erosion when employed back in the field, which may be due to failure in the braze joint due to insufficient bonding. Failure of these bits may occur because there is a gap between the hardfacing material and the cutter that has been brazed into the pocket. This gap may occur because an oxide layer on the displacement plug impeded the hardfacing material from bonding directly to the outer surface of the plug and created a gap between the displacement plug and the hardfacing material. This gap may be filled with brazing material upon brazing the cutter into the pocket. The brazing material is more susceptible to erosion and failure during bit operation than the hardfacing material, which is generally stronger and tougher than the brazing material.
Reference is made to U.S. Pat. No. 6,568,491 to Matthews, III, which discloses the application of a refractory metal layer to a displacement plug before applying hardfacing material to the bit. However, application of the refractory metal layer is a time consuming and costly step in the process of repairing or reinforcing a drill bit.
Reference is also made to U.S. Patent Application Publication No. 2002/0035895 of Peter M. Davies, et al., which discloses application of hardfacing material to a drill bit without the use of a displacement and subsequently removing the hardfacing material to install a cutting element.